Diacetyl measurement method

Abstract

To provide a method that can simply measure diacetyl included in a fermented food product and the like while discriminating the diacetyl included therein from acetoin.SOLUTION: A measurement method of diacetyl density in a sample in which a hydroxylation aqueous alkali solution, α-naphthol and creatine are added to the sample to measure absorbance is configured to measure absorbance at two pints of a reaction time in a time zone overlapping a time zoom in which absorbance of the diacetyl reaches a plateau with a time zone in which absorbance of acetoin linearly changes; and calculate density of the diacetyl by following expressions (1) to (4) from these absorbance. A relation expression (1): A1=DA+AC+H, a relation expression (2): AC / T1=(A2-A1) / (T2-T1), a relation expression (3): DA=[(T2*A1-T1*A2) / (T2-T1)]-H, and a proportional relation expression of a calibration curve (4): [diacetyl density]=k*DA, (in which A1 is indicative of absorbance at a time T1, A2 is indicative of absorbance at a time T2, DA is indicative of absorbance of the diacetyl, AC is indicative of absorbance of the acetoin, H is indicative of an average value of absorbance, which is coloring absorbance belonging to impurities included in the sample serving as a measurement object, right after a coloring reaction of the sample (0 minute) and after one minute goes by, and k is indicative of a proportional coefficient in the calibration curve of the density and absorbance of the diacetyl.)SELECTED DRAWING: None

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